Wireless mobile communication networks are ubiquitous in many parts of the world.
As technologies advance, improvements in network capacity, speed, bandwidth, latency, flexibility, and overall sophistication continue to improve. This results in a succession of versions, or revisions, of technical specifications for a given protocol or access technology, each version adding capabilities, such as advanced operating modes (e.g., discontinuous operations for power savings), multiple antennas, multiple carriers, different duplex modes, and the like.
One advanced feature of many third-generation wireless communication protocols is the provision for multiple signal carrier frequencies, or “carriers,” known in the art as Carrier Aggregation (CA). By sending and receiving traffic on more than one carrier, networks may dramatically increase the communication bandwidth to suitably-equipped User Equipment (UE). In CA, a Primary downlink and uplink carrier (PCell) are defined for each UE, and one or more Secondary carriers SCell in the downlink, uplink, or both, may additionally be configured.
Modern wireless networks are characterized by adaptive operation, in which system parameters are constantly adapted to conform to changing network conditions. This requires UEs to measure system conditions, and report these measurements to the network. Additionally, advanced network management functions such as Self Optimizing Networks (SON) are also based on conditions measured and reported by UEs. Furthermore, many network functions, such as positioning, require extensive, although sporadic, signaling between a UE and the network. Much of this signaling between a UE and the network (in both uplink and downlink) occurs in a disjoint manner—that is, in irregular (noncontiguous) subframes, or according to various patterns in which individual transmissions are spread out over time, and occur in noncontiguous subframes. The disjoint nature of such singling is not an issue if a UE remains tuned to the same carrier.
In carrier aggregation, when the network activates, deactivates, configures or de-configures one or more Secondary Cells (SCell) of a UE, the UE is required to engage in various “overhead” signaling with the network on the SCell to effect the change. During this time, any function requiring a UE measurement, or disjoint signaling on a Primary Cell (PCell) (or a different SCell), may be impaired, as the UE will “miss” some or all of the signaling, and is unable to transmit measurement data. Some disjoint signaling, such obtaining and reporting System Information on inter-frequency or inter-Radio Access Technology (RAT) cells, may take on the order of seconds, which is a very long duration in the context of modern wireless communication networks. Accordingly, the performance degradation associated with the missed measurements, or of the function engaging in disjoint signaling, may be severe.
The Background section of this document is provided to place embodiments herein in technological and operational context, to assist those of skill in the art in understanding their scope and utility. Unless explicitly identified as such, no statement herein is admitted to be prior art merely by its inclusion in the Background section.